Ordered on 23 September 1916, the U-boat was built at the AG Weser shipyard in Bremen and commissioned on 24 November 1917, under the command of Kapitänleutnant Günther Krech.

On her second patrol, she was picked up by HM Drifter Coreopsis II [Note 2] off the coast of Belfast, Northern Ireland on 30 April 1918, after she was partly flooded through a semi-open hatch while trying to evade attack by the British vessel.

[6] Under interrogation, the captain is reported to have said that the submarine had surfaced the night before to recharge the batteries and had been attacked by a large sea creature, a "strange beast" that rose out of the deep and damaged the vessel, leaving it unable to submerge.

[7][8] Engineers working on an electricity cable, the Western HVDC Link, discovered the almost intact wreck of a UB-III class submarine, believed to be either UB-85 or UB-82, lying off the Galloway coast in October 2016.

[9] Dr Innes McCartney who identified the wreck said: "We are certainly closer to solving the so-called mystery of UB-85 and the reason behind its sinking - whether common mechanical failure or something that is less easily explained.